Verification of Thermal Performance Predictions of Prototypical Multi-Jet Impingement Helium-Cooled Divertor Module

Abstract

An experimental investigation of the thermal performance of the Helium-Cooled Multi-Jet (HEMJ) modular divertor design developed by the Karlsruhe Research Center (FZK) was previously performed at Georgia Tech using air at Reynolds numbers (Re) spanning those at which the actual He-cooled divertor is to be operated. More recently, another experimental investigation was performed by the Georgia Tech group for a similar finger-type divertor module using both air and He as coolants. The results of these experiments suggest that, in addition to matching Re, dynamic similarity between the air and He experiments requires that a correction be made to account for the differences in the relative contributions of convection and conduction (through the divertor walls) to the overall heat removal rate by the module. This correction factor depends on the thermal conductivity ratio of the solid to the coolant. Experiments similar to those previously conducted have therefore been performed using air, argon, or He as coolant for test sections constructed of brass or steel thus covering a wide range of thermal conductivity ratio. The resultant correlation between Re, the heat removal rate, and the thermal conductivity ratio from these experiments can be used to predict the thermal performance of HEMJlike divertors at prototypical operating conditions.